The present invention relates to semiconductor integrated circuits, and more particularly, to an interconnection design between a driver and a load which increases a drive signal and decreases a pin count of an integrated circuit.
The sophistication of a present-day electronic system is the result of the complex functions handled by integrated circuits making up the electronic system. Within a single silicon chip or wafer, numerous integrated circuits are fabricated. Each integrated circuit may comprise many millions of transistors, including associated diodes, resistors, and capacitors, interconnected to form complex electronic systems capable of performing various functions. The integrated circuit, also known as a die, is secured in an encapsulating package having leads, also known as pins, for connecting the integrated circuit to the overall electronic system or product incorporating numerous integrated circuits via a printed circuit board.
Semiconductor integrated circuits comprise the majority of electronic circuits in computers and other digital electronic products. Integrated circuits can be configured, for example, as a central processing unit (CPU), a programmable logic array (PLA), an application specific integrated circuit (ASIC), or a digital signal processor (DSP). Both the sophistication and speed of operation of these integrated circuits has rapidly increased due to improvements in integrated circuit manufacturing technologies resulting in smaller and faster devices.
Within an integrated circuit, numerous drivers are fabricated adjacent to die pins associated with the outputs of the integrated circuit. The numerous drivers each drive a signal from within the integrated circuit to other integrated circuits or components of the overall electronic system. A driver is a known device in integrated circuit technology. A driver normally consists of a transistor design capable of receiving an input signal, manipulating the signal in one of a variety of ways, such as amplifying the signal, and providing an output signal. In prior integrated circuit designs, each driver and associated die pin is electrically coupled to a printed circuit board pin through an encapsulating package. The package provides both protection for the fragile, silicon integrated circuit and a connection between the integrated circuit and the printed circuit board. The printed circuit board facilitates interconnection between the integrated circuit and other integrated circuits or electrical components within a particular system through board traces or other electrical connections.
In prior integrated circuit designs, each driver and associated die pin is electrically connected to one or more printed circuit board pins, which in turn is connected to one or more loads in the form of integrated circuits or electrical components. If a single die pin and associated drive is connected to more than one printed circuit board pin, a fanout design, as is known in the art, is employed. A fanout design transmits a signal from a single driver to multiple loads (integrated circuits or electrical components).
The speed and frequency of digital electronic products and computers are constantly increasing. With this increasing speed, it is becoming ever difficult to provide an integrated circuit having drivers capable of driving signals to one or more loads, such as other integrated circuits or electrical components within the system, at elevated frequencies. In addition, due to the increased number of integrated circuits and other components which can be included on a single printed circuit board, the number of printed circuit board pins is insufficient for interconnection. Thus, there is a need for an integrated circuit design which will provide an increased drive signal between one or more integrated circuits at elevated frequencies utilizing a minimal number of printed circuit board pins.
The present invention is a system and method for providing a signal to a load. The invention provides increased signal flow to a load, while reducing the number of printed circuit board pins used to transmit the increased signal to the load. In one embodiment, the integrated circuit receives power from an external source. A first driver is electrically coupled to the power source such that the power source provides power to the first driver. The first driver receives a first input signal from within the integrated circuit and provides a first output signal at an output. A second driver is electrically coupled to the power source such that the power source provides power to the second driver. The second driver receives a second input signal from within the integrated circuit and provides a second output signal at an output. An electrically coupling device couples the first and second signals at the outputs of the first and second drivers to produce a combined signal. The electrically coupling device provides the combined signal to a load.
The combined signal provided to the load by the electrically coupling device provides an increased drive signal to the load. Therefore, while any one signal is not propagating at a faster rate, multiple signals are transmitted to the load in the same amount of time as a single signal previously reached the load, such that the strength of the overall drive signal received by the load is increased. In addition, the pin count for the associated printed circuit board is decreased since two or more driver signals are supplied to a single pin.
In one embodiment, the output of at least two drivers are electrically coupled and the single combined signal is connected to a load via a single printed circuit board pin. In another embodiment, a plurality of pairs of outputs of drivers are electrically coupled and provided to various loads, thereby further increasing the driver signal and decreasing the printed circuit board pin count while supplying increased drive signals to multiple loads. In yet another embodiment, each electrically coupling device is a conductor, such as a wire. The interconnection of numerous driver outputs further reduces the printed circuit board pin count, while providing an increased drive signal to the load. In yet still another embodiment, a single conductor electrically couples the combined signal to a plurality of loads. Numerous jumper conductors permit the combined signal to propagate to the plurality of loads.